1. Field of the Invention
The present invention relates to a webbing take-up device configuring a vehicle seat belt apparatus, and in particular relates to a webbing take-up device suited to installing in a seat back of a vehicle mounted seat with reclining mechanism.
2. Related Art
In a webbing take-up device disclosed in Japanese Patent Application Laid-Open (JP-A) No. 10-157569, an inertia mass body (referred to as a sensor ball in JP-A No. 10-157569) is placed on a bracket of an acceleration detection means (referred to as an acceleration sensor in JP-A No. 10-157569). The bracket is attached to a hanger so as to be capable of rotatable about an axis whose axial direction is as the same direction of the axial direction of a spool. When a retractor base is tilted about an axis whose axial direction is as the same axial direction of the spool axial direction, the bracket accordingly rotates relative to the retractor base, as the bracket attempts to maintain the same attitude as in a state prior to the retractor base rotating.
The bracket is configured so as to be capable of rotating with respect to the retractor base such as described above. Accordingly, the angle of incline of the face on which the inertia mass body is placed is made small such that the inertia mass body rolls in the event of the bracket rotating at a time of sudden vehicle deceleration. However, the bracket does not rotate in the axial direction of rotation thereof (mainly in the vehicle left-right direction). The inertia mass body accordingly readily rolls in the axial direction of rotation of the bracket, resulting in a difference in rolling sensitivities of the inertia mass body between in the rotation axial direction and in the direction orthogonal to the rotation axial direction (mainly in the vehicle front-rear direction).